package net.kanawo.cemodern.gui;

import net.kanawo.cemodern.tile.TileEMCBuilder;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.player.InventoryPlayer;
import net.minecraft.inventory.IInventory;
import net.minecraft.inventory.Slot;
import net.minecraft.item.ItemStack;

import buildcraft.builders.gui.ContainerBuilder;
import buildcraft.core.lib.gui.widgets.ScrollbarWidget;

/**
 * The Builder container plus an EMC consume slot. Extending {@link ContainerBuilder} keeps BuildCraft's requirement
 * tooltips and GUI watcher handling.
 */
public class ContainerEMCBuilder extends ContainerBuilder {

    /** Matches the slot frame at (132, 26) in emcbuilder.png. */
    public static final int CONSUME_SLOT_X = 133;
    public static final int CONSUME_SLOT_Y = 27;

    private static final int PLAYER_SLOTS = 9 * 4;

    /** Index of the consume slot; the builder and player slots are all before it. */
    private final int consumeSlot;

    public ContainerEMCBuilder(IInventory playerInventory, TileEMCBuilder builder) {
        super(playerInventory, builder);

        // A builder made from a blueprint has no owner yet; whoever opens it first takes it.
        if (!builder.getWorldObj().isRemote && playerInventory instanceof InventoryPlayer) {
            builder.claimOwner(((InventoryPlayer) playerInventory).player);
        }

        consumeSlot = inventorySlots.size();
        addSlotToContainer(new SlotEMCConsume(builder, CONSUME_SLOT_X, CONSUME_SLOT_Y));
    }

    public ScrollbarWidget getScrollbar() {
        return scrollbarWidget;
    }

    /**
     * Same behaviour as BuildCraftContainer, which assumes the player inventory is the last 36 slots; the consume slot
     * comes after it here. Shift-clicking never moves items into the consume slot.
     */
    @Override
    public ItemStack transferStackInSlot(EntityPlayer player, int slotIndex) {
        if (slotIndex == consumeSlot) {
            return null;
        }

        Slot slot = (Slot) inventorySlots.get(slotIndex);

        if (slot == null || !slot.getHasStack()) {
            return null;
        }

        int playerStart = consumeSlot - PLAYER_SLOTS;
        int hotbarStart = consumeSlot - 9;
        ItemStack stack = slot.getStack();
        ItemStack original = stack.copy();

        if (slotIndex >= playerStart) {
            if (!shiftIntoBuilder(stack, playerStart)) {
                boolean fromHotbar = slotIndex >= hotbarStart;

                if (!shiftItemStack(
                    stack,
                    fromHotbar ? playerStart : hotbarStart,
                    fromHotbar ? hotbarStart : consumeSlot)) {
                    return null;
                }
            }
        } else if (!shiftItemStack(stack, playerStart, consumeSlot)) {
            return null;
        }

        slot.onSlotChange(stack, original);

        if (stack.stackSize <= 0) {
            slot.putStack(null);
        } else {
            slot.onSlotChanged();
        }

        if (stack.stackSize == original.stackSize) {
            return null;
        }

        slot.onPickupFromSlot(player, stack);
        return original;
    }

    private boolean shiftIntoBuilder(ItemStack stack, int builderSlots) {
        for (int i = 0; i < builderSlots; i++) {
            Slot slot = (Slot) inventorySlots.get(i);

            if (slot.isItemValid(stack) && shiftItemStack(stack, i, i + 1)) {
                return true;
            }
        }

        return false;
    }
}